A dynamoelectric machine includes a rotor having a rotor core made by stacking core materials, for example, by die-casting of aluminum. The core material is made by punching band-shaped magnetic steel sheets, for example. However, the band-shaped magnetic steel sheets are made by rolling, which results in variations in a thickness of the magnetic steel sheets. When the magnetic steel sheets have variations in the thickness, the core materials obtained from the magnetic steel sheets also have variations in the thickness. Accordingly, when the core materials are stacked without consideration of directions of the core materials in order that a rotor core may be obtained, obtained rotor cores sometimes vary in dimensions. In view of the problem, it is proposed to axially divide the rotor core into two parts and to stack the divided parts circumferentially shifted from each other by a predetermined angle, for example, 180°.
However, there has conventionally been no way to check, after the stacking, that the core materials are stacked while being circumferentially shifted by the predetermined angle. As a result, when manually stacked, the core materials are sometimes stacked without being shifted circumferentially by the predetermined angle.